Some 1988-1991 Rivieras that have been parked at an angle (i.e., on a hill or two wheels in a ditch) either front to back or side to side may exhibit a false low oil message. The angle of the vehicle causes the oil in the oil pan to flow away from the oil level switch. This condition is normal and will not be corrected by replacing the oil level switch or oil pan.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.